DE10228873A1 - Aqueous polyurethane dispersions - Google Patents

Abstract

Aqueous dispersions containing a polyurethane composed of DOLLAR A a) diisocyanates, DOLLAR A b) diols, of which DOLLAR A b¶1¶) 10 to 100 mol%, based on the total amount of diols (b), a molecular weight of 500 to 5000, and DOLLAR A b¶2¶) 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol, DOLLAR A c) of the monomers (a ) and (b) different monomers with at least one isocyanate group or at least one group which is reactive toward isocyanate groups and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water dispersibility of the polyurethanes, DOLLAR A d) optionally further of the monomers (a) to (c) various polyvalent compounds with reactive groups, which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and DOLLAR A e) optionally v on the monomers (a) to (d) different monovalent compound with a reactive group, which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group, DOLLAR A, the aqueous dispersions additionally 0.0005 to 0, 05 mol, per 100 g of solid polyurethane of a salt of polybasic carboxylic acids of alkali metals or ammonium, which has a molar mass of less than 1000 g / mol.

Description

• a₎ Diisocyanaten,
• b₎ Diolen, von denen
• b₁) 10 bis 100 mol-%, bezogen auf die Gesamtmenge der Diole (b), ein Molekulargewicht von 500 bis 5000 aufweisen, und
• b₂) 0 bis 90 mol-%, bezogen auf die Gesamtmenge der Diole (b), ein Molekulargewicht von 60 bis 500 g/mol aufweisen,
• c) von den Monomeren (a) und (b) verschiedene Monomere mit wenigstens einer Isocyanatgruppe oder wenigstens einer gegenüber Isocyanatgruppen reaktiven Gruppe, die darüber hinaus wenigstens eine hydrophile Gruppe oder eine potentiell hydrophile Gruppe tragen, wodurch die Wasserdispergierbarkeit der Polyurethane bewirkt wird,
• d) gegebenenfalls weiteren von den Monomeren (a) bis (c) verschiedenen mehrwertigen Verbindungen mit reaktiven Gruppen, bei denen es sich um alkoholische Hydroxylgruppen, primäre oder sekundäre Aminogruppen oder Isocyanatgruppen handelt und
• e) gegebenenfalls von den Monomeren (a) bis (d) verschiedenen einwertigen Verbindungen mit einer reaktiven Gruppe, bei der es sich um eine alkoholische Hydroxylgruppe, eine primäre oder sekundäre Aminogruppe oder eine Isocyanatgruppe handelt,

wobei die wässrigen Dispersionen zusätzlich 0,0005 bis 0,05 mol, pro 100 g festes Polyurethan eines Salzes mehrbasiger Carbonsäuren der Alkalimetalle oder des Ammoniums enthalten, welches eine Molmasse von weniger als 1000 g/mol aufweist.The present invention relates to aqueous dispersions containing a polyurethane composed of

• a ₎ diisocyanates,
• b ₎ diols, of which
• b ₁ ) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000, and
• b ₂ ) 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol,
• c) monomers different from the monomers (a) and (b) with at least one isocyanate group or at least one group which is reactive toward isocyanate groups and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water-dispersibility of the polyurethanes,
• d) optionally further polyvalent compounds with reactive groups which differ from the monomers (a) to (c) and which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups and
• e) optionally monohydric compounds which differ from the monomers (a) to (d) and have a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group,

wherein the aqueous dispersions additionally contain 0.0005 to 0.05 mol, per 100 g of solid polyurethane of a salt of polybasic carboxylic acids of the alkali metals or ammonium, which has a molar mass of less than 1000 g / mol.

The invention further relates to Process for coating, gluing and impregnating objects different materials with these dispersions, with these Dispersions coated, glued and impregnated objects, as well the use of the dispersions according to the invention as coating materials.

The use of aqueous dispersions containing polyurethanes for coating substrates such as textiles or leather has long been known ( EP-A 595149 ). In the production of such aqueous polyurethane dispersions (hereinafter also referred to as PU dispersions), the addition reaction, ie the reaction of the individual monomers with one another, is often carried out using catalysts.

Following the implementation of the Individual monomers are then dispersed Polyurethane in water. The dispersions obtained often have one undesirable high viscosity.

In the EP-A 622436 It is described to lower the viscosities of aqueous polyurethane dispersions by adding salts of polyacrylic acid in order to modify their property profile and to obtain low-viscosity dispersions. When adding the salts of polyacrylic acid, local over-concentrations are often observed, which lead to undesirable coagulum formation.

From the US-A 4,401,786 is known to add alkali metal salts of inorganic acids or of monobasic carboxylic acids to aqueous polyurethane dispersions to improve the blocking resistance. However, it is not apparent from this document to modify the viscosity of such dispersions with the aid of the alkali metal salts used.

In the DE-A 19541329 discloses to add special phthalic acid salts, which can also consist of polyurethanes, among other things, of hairspray dispersions, which are combined with an amine base accepted in cosmetics, in order in this way to improve their usability as hair setting agents.

Furthermore, the EP-A 369 271 remove to introduce special fluorinated carboxylic acid salts in polyurethane dispersions for the treatment of antistatic agents.

In none of the listed writings describes how the viscosity of the obtained or used Polyurethane dispersions can be modified without losing their to change other properties.

The present invention was therefore based on the task of remedying the disadvantages described and to develop improved PU dispersions whose viscosity is clear can be modified without sustaining their other properties to change, for example without negatively affecting their particle size. Furthermore, the object of the present invention extends also on the production of new PUR dispersions with a higher solids content, that are still easy to process.

Accordingly, the aqueous dispersions defined at the outset and a process for their preparation have been found. Furthermore, a process for the production of coatings, bonds and impregnations was developed. Furthermore, the present invention extends to the glued and coated objects and their use as hydrolysis-resistant coating.

The aqueous dispersions according to the invention contain polyurethanes which, in addition to other monomers, are derived from diisocyanates a ₎ , preference being given to using those diisocyanates a ₎ which are customarily used in polyurethane chemistry.

Particularly worth mentioning as monomers (a) are diisocyanates X (NCO) ₂ , where X represents an aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms. Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,2-bis (4-isocyanatocyclohexyl) - propane, trimethylhexane diisocyanate, 1,4-diisocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the Isomers of bis (4-isocyanatocyclohexyl) methane (HMDI) such as the trans / trans, the cis / cis and the cis / trans isomers and mixtures consisting of these compounds.

Such diisocyanates are commercially available available.

As mixtures of these isocyanates especially the mixtures of the respective structural isomers of diisocyanatotoluene and diisocyanato-diphenylmethane is of particular importance the mixture of 80 mol% 2,4-diisocyanatotoluene and 20 mol% 2,6-diisocyanatotoluene suitable. Furthermore, the mixtures of aromatic isocyanates such as 2,4 diisocyanatotoluene and / or 2,6-diisocyanatotoluene with aliphatic or cycloaliphatic isocyanates such as hexamethylene diisocyanate or IPDI particularly geous, with the preferred mixing ratio of aliphatic to aromatic isocyanates 4: 1 to 1: 4.

To build the polyurethanes can one as connections except the aforementioned also use isocyanates, which in addition to the free Isocyanate groups further blocked isocyanate groups, e.g. Wear uretdione groups.

With regard to good film formation and elasticity come as diols (b) primarily higher molecular weight diols (b1) Consider having a molecular weight of about 500 to 5000, preferably have from about 1000 to 3000 g / mol.

The diols (b1) are, in particular, polyester polyols which are known, for example, from Ullmanns Encyklopadie der Technische Chemie, 4th edition, volume 19, pages 62 to 65. Polyester polyols are preferably used which are obtained by reacting dihydric alcohols with dihydric carboxylic acids. Instead of the free polycarboxylic acids, the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols or their mixtures can also be used to prepare the polyester polyols. The polycarboxylic acids can be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and optionally substituted, for example by halogen atoms, and / or unsaturated. Examples include: suberic acid, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylene tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic acid, fatty acid, maleic acid, maleic acid, fatty acid, maleic acid, maleic acid, fatty acid. Dicarboxylic acids of the general formula HOOC- (CH ₂ ) _y -COOH are preferred, where y is a number from 1 to 20, preferably an even number from 2 to 20, for example succinic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid.

Examples of polyhydric alcohols are ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butene-1,4-diol, butyne-1,4-diol, pentane-1 , 5-diol, neopentyl glycol, bis (hydroxymethyl) cyclohexanes such as 1,4-bis (hydroxymethyl) cyclohexane, 2-methyl-propane-1,3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol , Polypropylene glycol, dibutylene glycol and polybutylene glycols. Alcohols of the general formula HO- (CH ₂ ) _x -OH are preferred, where x is a number from 1 to 20, preferably an even number from 2 to 20. Examples include ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-l, 8-diol and dodecane-1,12-diol. Neopentyl glycol is also preferred.

Also come polycarbonate diols, such as by reacting phosgene with an excess of as structural components for the polyester polyols called low molecular weight alcohols can be into consideration.

Lactone-based polyester diols are also suitable, these being homopolymers or copolymers of lactones, preferably addition products of lactones with terminal hydroxyl groups onto suitable difunctional starter molecules. Suitable lactones are preferably those which are derived from compounds of the general formula HO- (CH ₂ ) _z -COOH, where z is a number from 1 to 20 and an H atom of a methylene unit also by a C ₁ - to C ₄ -alkyl radical may be substituted. Examples are ε-caprolactone, β-propiolactone, γ-butyrolactone and / or methyl-ε-caprolactone and mixtures thereof. Suitable starter components are, for example, the low molecular weight dihydric alcohols mentioned above as the structural component for the polyester polyols. The corresponding polymers of ε-caprolactone are particularly preferred. Lower polyester diols or polyether diols can also be used as starters for the preparation of the lactone polymers. Instead of the polymers of lactones, they can also correspond the chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones are used.

In addition, polyether diols are suitable as monomers (b1). They are in particular by polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with themselves, for example in the presence of BF ₃ or by addition of these compounds, if appropriate in a mixture or in succession, to starting components with reactive hydrogen atoms, such as alcohols or amines, for example Water, ethylene glycol, propane-1,2-diol, propane-1,3-diol, 1,2-bis (4-hydroxydiphenyl) propane or aniline are available. Polytetrahydrofuran with a molecular weight of 240 to 5000, and especially 500 to 4500, is particularly preferred. Mixtures of polyester diols and polyether diols can also be used as monomers (b1).

Also suitable are polyhydroxyolefins, preferably those with 2 terminal hydroxyl groups, for example α, -ω-dihydroxypolybutadiene, α, -ω-dihydroxypolymethacrylic ester or α, -ω-dihydroxypolyacrylic ester as monomers (c1). Such connections are for example from the EP-A 0622378 known. Other suitable polyols are polyacetals, polysiloxanes and alkyd resins.

The polyols can also be used as mixtures in a ratio of 0.1 : 1 to 1: 9 can be used.

The hardness and the modulus of elasticity the polyurethane can be increased if as diols (b) in addition to the diols (b1) also low molecular weight diols (b2) with a molecular weight of about 60 to 500, preferably from 62 to 200 g / mol.

Above all, as monomers (b2) the structural components of the for the production of short-chain alkane diols called polyester polyols used, with diols having 2 to 12 carbon atoms, unbranched diols with 2 to 12 carbon atoms and an even number of carbon atoms as well Pentane-1,5-diol and neopentyl glycol are preferred.

The proportion of diols (b1) is preferably based on the total amount of diols (b) 10 to 100 mol% and Proportion of monomers (b2), based on the total amount of diols (b) 0 to 90 mol%. The ratio of the diols (b1) to the is particularly preferably Monomers (b2) 0.1: 1 to 5: 1, particularly preferably 0.2: 1 to 2: 1.

To the water dispersibility of the To achieve polyurethanes, the polyurethanes are next to the components (a), (b) and optionally (d) from components (a), (b) and (d) various monomers (c) having at least one isocyanate group or at least one opposite Isocyanate group reactive group and moreover at least one hydrophilic Group or a group which can be converted into a hydrophilic group, built up. In the following text the term "hydrophilic groups or potentially hydrophilic Groups "with" (potentially) hydrophilic Groups ". The (Potentially) hydrophilic groups react significantly with isocyanates slower than the functional groups of the monomers that build up serve the main polymer chain.

The proportion of components with (potentially) hydrophilic groups on the total amount of components (a), (b), (c), (d) and (e) is generally dimensioned so that the molar amount of the (potentially) hydrophilic groups, based on the amount by weight all monomers (a) to (e), 30 to 1000, preferably 50 to 500 and is particularly preferably 80 to 300 mmol / kg.

With the (potentially) hydrophilic Groups can be non-ionic or preferably (potentially) ionic act hydrophilic groups. It is recommended, especially anionic to use hydrophilic groups.

As non-ionic hydrophilic groups polyethylene glycol ethers in particular come from preferably 5 to 100, preferably 10 to 80 repeating ethylene oxide units, in Consideration. The content of polyethylene oxide units is generally 0 to 10, preferably 0 to 6 wt .-%, based on the amount by weight of all Monomers (a) to (e).

Preferred monomers with nonionic hydrophilic groups are polyethylene oxide diols, polyethylene oxide monools and the reaction products of a polyethylene glycol and a diisocyanate, which carry a terminally etherified polyethylene glycol residue. Such diisocyanates and processes for their preparation are in the patents US-A 3,905,929 and US-A 3,920,598 specified.

Ionic are hydrophilic groups especially anionic groups such as the sulfonate, the carboxylate and the phosphate group in the form of its alkali metal or ammonium salts and cationic groups such as ammonium groups, especially protonated tertiary Amino groups or quaternary Ammonium groups.

Potentially ionic hydrophilic groups are primarily those that are easy to neutralize, hydrolysis or quaternization reactions in the above ionic have hydrophilic groups transferred, e.g. e.g. Carboxylic acid groups or tertiary Amino groups.

(Potentially) ionic monomers (c) are, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 4th Edition, Volume 19, pp. 311-313 and, for example, in DE-A 1 495 745 described in detail.

As (potentially) cationic monomers (c), monomers with tertiary amino groups are of particular practical importance, for example: tris (hydroxyalkyl) amines, N, N'-bis (hydroxyalkyl) alkylamines, N-hydroxyalkyl dialkylamines, tris - (aminoalkyl) amines, N, N'-bis (aminoalkyl) alkylamines, N-aminoal kyl-dialkylamines, the alkyl radicals and alkanediyl units of these tertiary amines independently of one another consisting of 1 to 6 carbon atoms. Also suitable are polyethers having tertiary nitrogen atoms and preferably having two terminal hydroxyl groups, such as are obtainable in a conventional manner, for example by alkoxylation of two amines having hydrogen atoms bonded to amine nitrogen, for example methyl amine, aniline or N, N'-dimethylhydrazine. Such polyethers generally have a molecular weight between 500 and 6000 g / mol.

These tertiary amines are converted into the ammonium salts either with acids, preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids or strong organic acids, or by reaction with suitable quaternizing agents such as C ₁ -C ₆ -alkyl halides or benzyl halides, for example bromides or chlorides.

in welcher R¹ und R² für eine C₁- bis C₄-Alkandiyl-Einheit und R³ für eine C₁- bis C₄-Alkyl-Einheit steht und vor allem Dimethylolpropionsäure (DMPA) bevorzugt.Suitable monomers with (potentially) anionic groups are usually aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids which carry at least one alcoholic hydroxyl group or at least one primary or secondary amino group. Preference is given to dihydroxyalkyl carboxylic acids, especially those with 3 to 10 carbon atoms, such as those in US-A 3 412 054 are described. In particular, compounds of the general formula (c _l )

in which R ¹ and R ^{2 represent} a C ₁ to C ₄ alkanediyl unit and R ^{3 represents} a C ₁ to C ₄ alkyl unit and especially dimethylolpropionic acid (DMPA) is preferred.

Corresponding ones are also suitable dihydroxysulphonic and dihydroxyphosphonic acids such as 2,3-dihydroxypropanephosphonic acid.

Otherwise suitable are dihydroxyl compounds with a molecular weight above 500 to 10000 g / mol with at least 2 carboxylate groups, which from the DE-A 3 911 827 are known. They can be obtained by reacting dihydroxyl compounds with tetracarboxylic dianhydrides such as pyromellitic dianhydride or cyclopentantetracarboxylic dianhydride in a molar ratio of 2: 1 to 1.05: 1 in a polyaddition reaction. Particularly suitable dihydroxyl compounds are the monomers (b2) listed as chain extenders and the diols (b1).

Suitable monomers (c) with amino groups reactive towards isocyanates are amino carboxylic acids such as lysine, β-alanine or those in the DE-A 2034479 mentioned adducts of aliphatic diprimary diamines with α, β-unsaturated carboxylic or sulfonic acids into consideration.

Such compounds obey, for example, the formula (c ₂ ) H ₂ NR ⁴ -NH-R ⁵ -X (c ₂ ) in the
- R ⁴ and R ⁵ independently of one another for a C ₁ to C ₆ alkanediyl unit, preferably ethylene
and X represents COOH or SO ₃ H.

Particularly preferred compounds of the formula (c ₂ ) are the N- (2-aminoethyl) -2-aminoethane carboxylic acid and the N- (2-aminoethyl) -2-aminoethanesulfonic acid or the corresponding alkali metal salts, Na being particularly preferred as the counter ion.

Also preferred are the adducts of the abovementioned aliphatic diprimary diamines with 2-acrylamido-2-methylpropanesulfonic acid, as described, for example, in the DE patent 1 954 090 are described.

If monomers with potentially ionic Groups can be used, their conversion into the ionic form before, during, however, preferably after the isocyanate polyaddition, because the ionic monomers in the reaction mixture often only difficult to solve. The sulfonate or carboxylate groups are particularly preferred in the form of their salts with an alkali ion or an ammonium ion as Counter ion.

The monomers (d) by the monomers (a) to (c) are different and which may also be constituents of the polyurethane are generally used for crosslinking or the chain extension. It are generally more than dihydric non-phenolic alcohols, Amines with 2 or more primary and / or secondary Amino groups as well as compounds in addition to one or more alcoholic Hydroxyl groups one or more primary and / or secondary amino groups wear.

Alcohols with a higher valency than 2, which is used to set a certain degree of branching or networking can serve are e.g. Trimethylolpropane, glycerin or sugar.

Also suitable are mono alcohols the next to the hydroxyl group another versus isocyanates like mono alcohols carry reactive groups with one or more primary and / or secondary Amino groups, e.g. Monoethanolamine.

Polyamines with 2 or more primary and / or secondary Amino groups are mainly used when the chain extension or crosslinking should take place in the presence of water, since amines usually faster than alcohols or water with isocyanates react. It is common required if watery Dispersions of cross-linked polyurethanes or with polyurethanes high molecular weight desired become. In such cases one proceeds in such a way that one Prepares prepolymers with isocyanate groups quickly in water dispersed and then by adding compounds with several amino groups reactive towards isocyanates chain extended or networked.

Suitable amines are generally polyfunctional amines in the molecular weight range from 32 to 500 g / mol, preferably from 60 to 300 g / mol, which have at least two amino groups, selected from the group of primary and secondary Amino groups included. Examples include diamines such as diaminoethane, Diaminopropanes, diaminobutanes, diaminohexanes, piperazine, 2,5-dimethylpiperazine, Amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine, IPDA), 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylenetriamine or 1,8-diamino-4-aminomethyloctane.

The amines can also be in blocked form, for example in the form of the corresponding ketimines (see, for example CA-A 1 129 128 ), Ketazine (see e.g. the US-A 4,269,748 ) or amine salts (see US-A 4,292,226 ) are used. Also oxazolidines, such as those in the US-A 4 192 937 used are masked polyamines which can be used for the production of the polyurethanes according to the invention for chain extension of the prepolymers. When using such capped polyamines, these are generally mixed with the prepolymers in the absence of water and this mixture is then mixed with the dispersion water or part of the dispersion water, so that the corresponding polyamines are released hydrolytically.

Mixtures of di- and triamines are used, particularly preferably mixtures of isophoronediamine (IPDA) and diethylene triamine (DETA).

The polyurethanes preferably contain 1 to 30, particularly preferably 4 to 25 mol%, based on the total amount of components (b) and (d) of a polyamine with at least 2 compared to isocyanates reactive amino groups as monomers (d).

Alcohols with a higher valency than 2, which is used to set a certain degree of branching or networking can serve are e.g. Trimethylolpropane, glycerin or sugar.

For can do the same thing also higher than monomers (d) be used as divalent isocyanates. Commercially available connections are, for example, the isocyanurate or the biuret of hexamethylene diisocyanate.

Monomers (e), if appropriate are also used are monoisocyanates, monoalcohols and monoprimary and secondary amines. Generally is their proportion not more than 10 mol%, based on the total molar amount of Monomers. These monofunctional compounds usually carry further functional groups such as olefinic groups or carbonyl groups and serve as an introduction of functional groups in the polyurethane that the dispersion or the crosslinking or further polymer-analogous implementation of the polyurethane enable. Consider this Monomers such as isopropenyl-α, α-dimethylbenzyl isocyanate (TMI) and esters of acrylic or methacrylic acid such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

Coats with one you get a particularly good property profile when essentially only aliphatic diisocyanates as monomers (a), cycloaliphatic diisocyanates or TMXDI and as monomer (b1) in essentially only polyester diols, built up from the aliphatic mentioned Diols and diacids, be used.

This combination of monomers is used in excellently complemented as component (c) by diamino acid salts; especially through the N- (2-aminoethyl) -2-aminoethanesulfonic acid, the N- (2-aminoethyl) -2-aminoethane carboxylic acid or their corresponding alkali salts, the Na salts being the most suitable, and a mixture of DETA / IPDA as component (d).

In the field of polyurethane chemistry is generally known, such as the molecular weight of the polyurethanes by choosing the proportions of the monomers reactive with one another and the arithmetic mean of the number of reactive functional groups per molecule can be adjusted.

• A) der Molmenge an Isocyanatgruppen und
• B) der Summe aus der Molmenge der Hydroxylgruppen und der Molmenge der funktionellen Gruppen, die mit Isocyanaten in einer Additionsreaktion reagieren können

0,5 : 1 bis 2 : 1, bevorzugt 0,8 : 1 bis 1,5, besonders bevorzugt 0,9 : 1 bis 1,2 : 1 beträgt. Ganz besonders bevorzugt liegt das Verhältnis A : B möglichst nahe an 1 : 1.Components (a) to (e) and their respective molar amounts are normally chosen so that the ratio A: B with

• A) the molar amount of isocyanate groups and
• B) the sum of the molar amount of the hydroxyl groups and the molar amount of the functional groups which can react with isocyanates in an addition reaction

0.5: 1 to 2: 1, preferably 0.8: 1 to 1.5, particularly preferably 0.9: 1 to 1.2: 1. The ratio A: B is very particularly preferably as close as possible to 1: 1.

The monomers (a) to (e) usually wear on average 1.5 to 2.5, preferably 1.9 to 2.1, particularly preferably 2.0 isocyanate groups or functional groups with isocyanates in an addition reaction can react.

The polyaddition of the components (a) to (e) for the preparation of the aqueous in the invention Dispersions of present polyurethane can at reaction temperatures from 20 to 180 ° C, preferably 70 to 150 ° C under normal pressure or under autogenous pressure.

The required response times are usually in the range of 1 to 20 hours, especially in the range of 1.5 up to 10 hours. It’s known in the field of polyurethane chemistry like the response time through a variety of parameters like temperature, Concentration of the monomers, reactivity of the monomers is influenced.

The reaction, ie the polyaddition of the monomers a ₎ , b ₎ , c ₎ and, if appropriate, d ₎ and e ₎ for the preparation of the PU dispersions according to the invention, can be catalyzed with the aid of organic or organometallic compounds. Suitable organometallic compounds include dibutyltin dilaurate, stannous octanoate or diazobicyclo (2,2,2) octane. Other suitable catalysts for the reaction of monomers a), b) and c) and optionally d) and e) are also salts of cesium, in particular cesium carboxylates.

As polymerizers for carrying out the Polyaddition come stirred kettles into consideration, especially when using solvents for one low viscosity and good heat dissipation is taken care of.

Preferred solvents are with water infinitely miscible, boiling point at normal pressure of 40 to 100 ° C and do not react or react only slowly with the monomers.

Most of the time, the dispersions are made by one of the following methods:
According to the "acetone process", an ionic polyurethane is produced from components (a) to (c) in a water-miscible solvent which boils at 100 ° C. under normal pressure. Sufficient water is added until a dispersion is formed in which water is the coherent phase.

The "prepolymer mixing process" differs of the acetone process in that not a fully reacted (potentially) ionic polyurethane, but first one Prepolymer is produced that carries isocyanate groups. The Components are chosen so that the definition A : B greater than 1.0 to 3, preferably 1.05 to 1.5. The prepolymer comes first dispersed in water and then optionally by reaction of isocyanate groups with amines that are more than 2 versus isocyanates carry reactive amino groups, crosslinked or with amines, the 2 towards isocyanates wear reactive amino groups, chain extended. A chain extension also takes place when no amine is added. In this In this case, isocyanate groups are hydrolyzed to amino groups remaining isocyanate groups of the prepolymers with chain extension react.

Usually if a solvent is used in the production of the polyurethane was used, the largest part of the solvent removed from the dispersion, for example by distillation reduced pressure. The dispersions preferably have a solvent content of less than 10% by weight and are particularly preferably free of solvents.

The dispersions generally have a solids content of 10 to 75, preferably 20 to 65% by weight and a viscosity of 10 to 1500 m Pas (measured at a temperature of 20 ° C. and a shear rate of 250 s ^-1 ).

Hydrophobic auxiliaries which can be difficult to distribute homogeneously in the finished dispersion, for example phenol condensation resins made from aldehydes and phenol or phenol derivatives or epoxy resins and others, for example in the DE-A 3903538 . 43 09 079 and 40 24 567 The polymers mentioned, which serve, for example, as adhesion improvers in polyurethane dispersions, can be added to the polyurethane or the prepolymer before the dispersion by the methods described in the two abovementioned documents.

The polyurethane dispersions can be commercially available auxiliary and additives such as blowing agents, defoamers, emulsifiers, thickeners and thixotropic agents, colorants such as dyes and pigments.

According to the invention, the aqueous dispersion additionally 0.0005 to 0.05 mol, in particular 0.001 to 0.01 mol, per 100 g solid polyurethane of a salt of polybasic carboxylic acids Alkali metals or ammonium. It is recommended that semi-neutralized polybasic carboxylic acids of the alkali metals or of ammonium.

This is preferably the case more basic with sodium, potassium, rubidium, cesium or ammonium salts organic carboxylic acid, which in diluted aqueous solution have a pH of 3 to 6.

Suitable polybasic organic carboxylic acids include adipic acid, malonic acid, succinic acid, phthalic acid in all isomeric forms, maleic acid, fumaric acid, tartaric acid, citric acid or a technical mixture of dicarboxylic acids (for example Pripol) and so-called low molecular weight polyesters Carboxylic acid groups and molecular weights below 1000.

Are particularly preferred Alkali salts or ammonium salts, especially sodium or potassium salts phthalic acid or adipic acid, especially potassium hydrogen phthalate, potassium hydrogen adipate or sodium hydrogen adipate.

According to a method also according to the invention for the production of the polyurethane dispersions according to the invention are after the reaction of the monomers a), b) and c) and optionally d) and e) to the polyurethane already during or after the dispersion the resulting polyurethane in water, the aqueous polyurethane dispersion additionally 0.0005 to 0.05 mol per 100 g of solid polyurethane, a salt of multi-base carboxylic acids the alkali salts or ammonium added, these salts being preferred have a molecular weight of less than 1000 g / mol.

According to another method according to the invention for the production of the polyurethane dispersions according to the invention the addition of the salts of polybasic carboxylic acids of the alkali metals or Ammonium before the resulting polyurethane is dispersed in water.

If the salts are added in a multi-base carboxylic acids into the dispersion, i.e. before, during or after dispersion, it is recommended to shape this 0.05 to 0.1 N more aqueous solutions add.

Are the salts of polybasic carboxylic acids Dispersion used, so can these can also be dissolved directly in the dispersing water.

The dispersions according to the invention are suitable for coating objects made of metal, plastic, paper, textile, leather or wood by them according to the common practice Process, e.g. by spraying or squeegees in the form of a film on these objects and the Dispersion dries.

In particular, the dispersions for coating objects made of plastic, paper, textile or leather if you have previously the dispersion turns into a foam by known methods and with this coated.

The aqueous dispersions are particularly suitable for the preparation of preparations as in the DE-A 19 605 311 are described. According to the teaching of the DE-A 19 605 311 used for the coating of textiles or fleeces. This treatment makes these materials flame-resistant, waterproof to liquid water and permeable to water vapor.

To produce the coated The aqueous dispersions according to the invention are textiles or nonwovens according to customary methods Process on the textile carrier materials applied, e.g. by squeegee or paint and the coated support material subsequently dried.

Objects made of metal, plastic, Paper, leather or wood can also be mixed with other items, preferably the aforementioned objects, glue by forming the aqueous dispersion of the invention a film on one of these objects and apply it before or after drying of the film with another object.

Articles made of textile, leather or Paper can be impregnated with the dispersions according to the invention, by looking at these items with the watery Dispersion soaks and subsequently dries.

The viscosity of the aqueous Polyurethane dispersions can be modify easily and very clearly without losing their other properties changed sustainably become. The method according to the invention also performs without huge technical effort, only using special salts polybasic carboxylic acids, too watery Polyurethane dispersions with easily adjustable viscosity.

experimental part

Example 1: Carboxylate Stabilized Polyurethane dispersion

600 g p THF 2000 with 0.25 g DBTL, 40.2 g DMPA and 155.6 g IPDI in 80 g acetone at 65 ° C and 0.8 bar pressure 4 h 20 min implemented. Then it is diluted with 520 g of acetone and to 30 ° C cooled. The NCO content is 0.9%. It is neutralized with 30.4 g of triethylamine and with 1000 g of water dispersed. The acetone is vacuumed at temperatures up to 42 ° C distilled off and the dispersion adjusted to 43.8% solids. It has a viscosity of 1060 mPas, pH = 7.8.

Example 2: Carboxylate Stabilized Polyurethane dispersion

Example 1 is repeated and the dispersion was set to 45%. Viscosity: 1260 mPas, pH = 8.0.

Example 3: Sulfonate stabilized Polyurethane dispersion

728 g of a polyester diol composed of adipic acid and 1,4-butanediol (OHZ = 46) are reacted with 0.15 g DBTL and 90 g IPDI in 290 g acetone at 60 ° C. and 0.5 bar. After 5 h, the mixture is diluted with 700 g of acetone and cooled to 50 ° C. The NCO content is 0.57%. It is mixed with 38.7 g of a 50% aqueous solution of Ami Noethanaminoethylsulfonic acid sodium salt chain extended for 10 min, diluted with 40 g water and then dispersed with 800 g demineralized water. The acetone is distilled off in vacuo at temperatures up to 42 ° C. and the dispersion is adjusted to 52% solids. It has a viscosity of 414 mPas, pH = 6.6.

Example 4-7:

The polyurethane dispersion from example 1 was with deionized water to a solids content of 40% or 35% set. In comparison, different buffer solutions were used.

In the following examples the effect of the buffer solutions according to the invention compared to the effects of other salts.

THF:

Tetrahydrofuran

DBTL:

Dibutylzinndilaurat

DMPA:

Dimethylolpropionsäure

IPDI:

1-Isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexan

NCO:

Isocyanat

FG:

Feststoffgehalt

K:

Kalium

Na:

Natrium

Used abbreviations:

THF:

tetrahydrofuran

DBTL:

dibutyltindilaurate

DMPA:

dimethylolpropionic

IPDI:

1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane

NCO:

isocyanate

FG:

Solids content

K:

potassium

N / A:

sodium

The viscosity was measured in a Physica Rheomat Viskolab LC 10 at 23 ° C and 250 s ¹ .

The particle size was measured using the Malvern Autosizer 2C measured.

Examples 15-19 describe the behavior a sulfonate stabilized polyurethane dispersion.

Example 20:

Production of a polyurethane dispersion using 0.05N K hydrogen phthalate solution.

The dispersion from Example 2 is repeated. After neutralization, 500 g 0.05N potassium hydrogen phthalate solution added and further dispersed with 250 g of demineralized water. The acetone will in a vacuum at temperatures up to 42 ° C distilled off and the dispersion adjusted to 45% solids. It has a viscosity of 250 mPas, pH = 7.7.

From the results presented shows that in the examples according to the invention 5, 7, 9, 10 and 11 in comparison to comparative examples 4, 6, 8, 12, 13 and 14 with the same particle size the viscosity clearly can be lowered.

Claims (16)

Aqueous dispersions containing a polyurethane composed of a ₎ diisocyanates, b ₎ diols, of which b _l) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000, and b _{2 )} 0 to 90 mol%, based on the total amount of the diols (b), have a molecular weight of 60 to 500 g / mol, c) monomers different from the monomers (a) and (b) with at least one isocyanate group or at least one group reactive toward isocyanate groups, which in addition carry at least one hydrophilic group or a potentially hydrophilic group, as a result of which the water dispersibility of the polyurethanes is effected, d) optionally further polyvalent compounds with reactive groups different from the monomers (a) to (c), which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups and e) optionally from the monomers (a) to (d) various monovalent compounds with a reactive group, which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group, the aqueous dispersions additionally 0.0005 to 0.05 mol, per 100 g of solid polyurethane Contain salt of polybasic carboxylic acids of alkali metals or ammonium, which has a molecular weight of less than 1000 g / mol. aqueous Dispersions according to claim 1, wherein as diisocyanates (a) 2,4- and 2,6-diisocyanatotoluene, 2,4'- and 4,4'-diisocyanatodiphenylmethane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), Tetramethylxylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI) and bis (-4-isocyanatocyclohexyl) methane (HMDI) can be used. Aqueous dispersions according to claims 1 or 2, wherein the diols (b ₁ ) are polyester diols, polyether diols or mixtures thereof. Aqueous dispersions according to Claims 1 to 3, diols having 2 to 12 carbon atoms being used as the diols (b ₂ ). aqueous Dispersions according to the claims 1 to 4, the monomers (c) being 2-aminoethyl-2-aminoethanesulfonic acid or the 2-aminoethyl-2-aminoethane carboxylic acid and their corresponding Alkali salts are used. aqueous Dispersions according to the claims 1 to 4, with dimethylolpropionic acid used as monomers (c) becomes. aqueous Dispersions according to the claims 1 to 6, the aqueous Dispersions an additional 0.001 up to 0.01 mol per 100 g solid polyurethane of the salt multi-base carboxylic acids the alkali metals or ammonium. aqueous Dispersions according to the claims 1 to 7, these semi-neutralized polybasic carboxylic acids Contain alkali metals or ammonium. aqueous Dispersions according to the claims 1 to 8, the aqueous Dispersions as salts of polybasic carboxylic acids. Salts of phthalic acid or of adipic acid the alkali metals or ammonium. Process for the preparation of aqueous dispersions containing a polyurethane composed of a ₎ diisocyanates, b ₎ diols, of which b _l) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000 , and b ₂₎ 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol, c) monomers different from the monomers (a) and (b) with at least one Isocyanate group or at least one group which is reactive towards isocyanate groups and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water-dispersibility of the polyurethanes, d) optionally further polyvalent compounds other than the monomers (a) to (c) with reactive compounds Groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups and e) optionally differ from the monomers (a) to (d) eden monovalent compounds with a reactive group, which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group, characterized in that first the monomers a), b), c) and optionally d) and e) together implemented and then dispersed in water, the aqueous dispersions additionally during or after the dispersion 0.0005 to 0.05 mol per 100 g of solid polyurethane, a salt of multi-based car bonic acids of alkali metals or ammonium is added, which has a molecular weight of less than 1000 g / mol. Process for the preparation of aqueous dispersions containing a polyurethane composed of a) diisocyanates, b) diols, of which b _l) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000 , and b ₂₎ 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol, c) monomers different from the monomers (a) and (b) with at least one Isocyanate group or at least one group which is reactive towards isocyanate groups and which additionally carry at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water-dispersibility of the polyurethanes, d) optionally further polyvalent compounds other than the monomers (a) to (c) with reactive compounds Groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups and e) optionally differ from the monomers (a) to (d) A monovalent compounds with a reactive group, which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group, characterized in that first the monomers a), b), c) and optionally d) and e) with one another implemented and then dispersed in water, the aqueous dispersions additionally 0.0005 to 0.05 mol per 100 g of solid polyurethane, a salt of polybasic carboxylic acids of alkali metals or ammonium, which has a molecular weight of less than 1000 g, before the dispersion / mol. Process for coating objects made of metal, plastic, Paper, textile, leather or wood, characterized in that one aqueous Dispersion according to the claims 1 to 9 in the form of a film on these objects and the dispersion dries. Process for gluing objects made of metal, plastic, Paper, textile, leather or wood, characterized in that one aqueous Dispersion according to the claims 1 to 9 in the form of a film on one of these objects and him before or after drying the film with another object assembles. Impregnation process of objects of textile, leather or paper, characterized in that one objects with the watery Dispersion according to the claims 1 to 9 soak and subsequently dries. objects the one with the watery one Dispersion according to the claims 1 to 9 are coated, glued or impregnated. Use of the aqueous Dispersions according to claims 1 to 9 as a coating for objects made of metal, plastic, paper, textile, leather or wood.